An outbreak of measles occurred in northeastern Florida (Bradford, Clay, Duval, Nassau, Putnam, and St. Johns counties) in 1991 and early 1992. A total of 193 confirmed cases of measles were reported to the Florida Department of Health and Rehabilitative Services (FDHRS). This report summarizes an investigation of the outbreak in Duval County (1990 population: 676,556), which reported 146 (76%) of the cases.

The outbreak in Duval County began in April 1991 and peaked in October 1991. The last case was reported in January 1992. Seventy-five (51%) cases were reported from three inner-city zip code areas in Jacksonville. The overall incidence of measles in Duval County was 22 cases per 100,000 population. The age-specific incidence was highest for children aged less than 5 years (205 cases per 100,000). Of the 146 reported measles cases, 111 (76%) occurred among children aged less than 5 years, including 42 (29%) among children aged